Monday, 16 June 2014

Creatures with a human torso and a fish tail have appeared
in the folklore and mythology of many cultures. 1 We know them as
mermen and mermaids and examples became a popular feature of travelling shows
and museums, Henry Gosse describing his great disappointment, as a boy, to
discover the advertised mermaid was “a shrivelled and blackened little thing
which might have been moulded in mud for aught I could see”. 1 It
must have looked a little like the specimen shown below.

Frank Buckland, like Gosse an eminent writer and lecturer on
Natural History, describes the body of merman he saw exhibited in London: 2

In the back parlour of the White
Hart, Vine-court, Spitalfields, high and dry upon a deal board, lay this
wonderful object - hideous enough to excite the wonder of the credulous, and
curious enough to afford a treat to the naturalist. Such a thing as a merman or
mermaid of course never really existed; I was therefore most anxious to examine
its composition, which, by the kindness of the landlady (a remarkably civil
woman), who removed the glass that covered her treasure, I was enabled to do.
The creature (a gentleman, not a lady specimen of the tribe) was from three to
four feet long. The upper part of its body was composed of the head, arms and
trunk of a monkey, and the lower part of a fish, which appeared to me to be a
common hake; and the head was really a wonderful composition: the
parchment-like hideous ears stood well forward, the skin of the nose when soft
had been moulded into a decided specimen of “the snub,” the forehead was
wrinkled into a frown, and the mouth “grinned a ghastly grin;” the curled lips
partly concealed a row of teeth, which in the upper jaw were of conical form
and sharp-pointed, taken probably from the head of a hake, whose body formed
the lower part of our specimen. the lower jaw contained these fish’s teeth, but
conspicuously in front was inserted a human incisor or front tooth, and a
vacant cavity showed that there once had been a pair of them. These were
probably placed there to show the “real human nature” of the monster. The head
had once been covered with hair; but visitors, anxious to obtain a lock of a merman’s
hair, had so plucked his unfortunate wig that only a few scattered hairs
remained: the relic-seekers are now, therefore, ignorantly treasuring in their
cabinets [of curiosities] hairs from the pate of an old red monkey.

Buckland also examined a mermaid, about “half the size of
her partner”. It, too, was formed from a monkey and a fish, but this time with
glass doll’s eyes rather than the leather ones of the merman, that had pupils
marked in black ink.

The popularity of such exhibits
waned in the mid-Nineteenth Century and Buckland comments “The good folks of England are getting every year
more and more educated, and mermaids do not take so well now as formerly..”. 2
The legendary P. T. Barnum advertised the mermaid in his museum with a
highly imaginative painting to attract in customers. Of course, he knew the
exhibit was not a mermaid and “Mr Barnum confessed that
he did not pursue his studies in Natural History too far, or he might learn too much.” 2 Barnum justified
the confidence trick by making no extra charge and there were many other things
for visitors to see. He was a showman after all.

Any Natural Historian would see immediately that these exhibited
mermen and mermaids were manufactured, yet reports of these
creatures in their natural environment have been made by generations of
sailors. These may have been sightings of sea mammals, especially manatees (left, below) and dugongs (right, below). One can only
conclude that they were distant sightings to merit the belief that they were mermen or mermaids, or perhaps the sailors had
been too long at sea and their imaginations had become overdeveloped?

Although no-one can believe in their existence in the real
world, mermaids have had a lasting appeal in fiction, film and other media. After
all, they come from another world and thus fit into the niche also occupied by
angels, fairies and dragons. The best known story is The Little Mermaid by H C Andersen 3 and this formed the
basis for the Disney film of the same name. Andersen describes how mermaids
lived at the bottom of the ocean and had a class system, with at least one
Royal Family that had six Princesses:

The whole day long they used to
play in the palace, down in the great halls where live flowers grew on the
walls. Whenever the high amber windows were thrown open the fish would swim in,
just as swallows dart into our rooms when we open the windows. But these fish,
now, would swim right up to the little princesses to eat out of their hands and
let themselves be petted.. .. Each little princess had her own small garden
plot, where she could dig and plant whatever she liked..

The story continues by describing how the princesses were
allowed to swim to the surface of the ocean for the first time on their fifteenth
birthday, reporting back on what each had seen. The youngest princess heard all
the amazing descriptions, but had to wait and wait for her turn.
When the day came and she arrived at the surface, she saw a handsome prince and
rescued him from drowning after he became unconscious. The mermaid princess wanted to marry the prince, not only for love, but also to acquire immortality of the soul, as this was a feature of humans that mermaids lacked, but which
could be acquired through marriage. The transformation from fish tail into
“props” (legs) required a special potion prepared by an underwater witch - who improbably
boiled the ingredients in “a caldron over the flames”. 3 The famous
statue of the Little Mermaid in Copenhagen celebrates the transition to props
from the fish tail and that explains why it appears like a nude of the period,
with the outline of the tail barely visible. In the Disney film, which uses
only superficial features of the complex story told by Andersen, the youngest princess
appears as a mermaid Barbie Doll, with what appears to be a pull-on lower fish
section and discretion maintained by having a bikini top.

One’s rational side finds all this a bit much, but the mermaids
and mermen in museums, side shows and literature are very obviously fantasy
creatures and we can all enjoy that. In a wider context, there must be other imaginary things that we take to be real, but it is not always easy to see that
this is so. Hopefully, Natural Historians are better able to differentiate the
two, just as Barnum intimated.

Wednesday, 4 June 2014

We had to choose four topics to study in the final year of
my Zoology degree. I took classes in Entomology, Crop Protection, Limnology and
Genetics and the first three represented my main interests at the time. Genetics
was added because I thought it would be useful to know something of this
developing branch of Biology. It was 1967, and a current student of Genetics
would barely recognise the subject matter of our course. There was little on genomes
and nothing on the techniques that are now commonplace in Molecular Genetics.
Our practical classes involved, among other things, making crosses between
fruit flies (Drosophila melanogaster)
and then counting each of the resulting categories of eye colour etc. in the
following week. Although this was fun, I found myself being as intrigued by the
larvae and pupae that were in the growth medium as I was in the adult flies.

Fruit flies emerge from a puparium (see below), the hardened
skin of the last larval stage, in which pupation and metamorphosis occur. This
re-organisation always amazes me, in the way it allows such different life
styles for the flying adult and the crawling larva. Indeed, the evolution of a
pupal stage allowed for the selection of these quite different body types and
the use of the last larval skin shows economy of materials, as no other outer
covering is required. Interestingly, the puparium splits at the same place in all
individuals to allow the adult fly to escape and that adds to my sense of
amazement.

Fruit fly larvae are maggots (in colloquial language), and
are remarkably similar in form to those of other, related, flies. We are all familiar
with the maggots produced by house flies and blow flies and some will have come
across the larvae of flesh flies (see below). Maggots crawl using muscle
contractions along the body, aided by raised ridges that run transversely, and the
contractions allow them to burrow through substrata. They are aided in their
burrowing by being “pointed”, as this allows pressure to be exerted at the
forward end of the animal, and they feed as they go, loosening the material in front.
The larval head is much reduced and maggots tear at fruit or flesh using two
mouth hooks that are extended and contracted, rasping away at whatever medium
they are moving through. Food is broken up into a semi-liquid form that can be
easily ingested, with saliva helping in this process.

Although those enjoying coarse fishing have a fondness for
maggots as bait, most people (even Creationists!) find them unpleasant. This aversion stems both from their movement and the locations
favoured by egg-laying adults - we have all encountered blow fly maggots in
our dustbins or seen them moving over the rotting flesh of dead animals. The
latter are of value to Forensic Entomologists, who can provide accurate
estimates of the time of death by looking at the age of maggots, and the succession
of various species, but, even these larvae are not looked upon with much
pleasure. However, they are excellent examples of a highly successful natural
design and their resistant cuticle makes them difficult to kill, as anyone
pouring pest-control chemicals on to a domestic infestation will agree. Perhaps more people will appreciate maggots when they realise just how effective they are in wound cleaning? All the life stages
are excellent examples of the wondrous powers of evolution in the selection of
genetic mutations.

That brings us back to Genetics and the use of Drosophila in research. The fruit fly
has become a very popular “model organism” and it has been used to investigate
many facets of gene expression, one of the most recent being in the genetics of
intelligence. 1 Modern Biology is characterised by a deterministic
approach based on knowing the genome of a small number of organisms, and trying
to find out which gene, or combinations of genes, control which processes.
Underlying this is the idea that humans share genes with other organisms so
that we can gain insights into the working of humans as a result. Many
Biologists have become so obsessed with the anthropocentric approach that they
ignore the Natural History of organisms and that is a pity. We know that Drosophila larvae and pupae are
fascinating in their design and evolution, but who would have thought that there
are Drosophila larvae living as
predators on other invertebrates in African streams? 2 One presumes
that the ancient ancestors of these flies were living in fruit that fell into
water and the resistant cuticle of the larvae, their rasping mouth hooks, and
their crawling and burrowing ability were excellent pre-adaptations for
becoming an aquatic predator. Now that’s really interesting, isn’t it?